Structural Characteristics of Intergovernmental Water Pollution Control Cooperation Networks Using Social Network Analysis and GIS in Yangtze River Delta Urban Agglomeration, China

Water pollution exhibits distinct negative externalities, necessitating trans-regional collaborative governance among basin governments. However, few studies have examined the structural features of water pollution collaboration networks among local governments in China from a spatial analysis perspective. This study focuses on 27 central cities in the Yangtze River Delta, collecting 109 policy texts and evidence of cooperative actions on water pollution governance among these cities. By utilizing a combination of social network analysis and GIS spatial analysis, the research visualizes the results and delves into the overall structure and internal features of the network. The results indicate that the density of the water pollution cooperation network is 0.75, suggesting that a relatively stable and closely connected network for collaborative governance of water pollution has been formed. Furthermore, the water pollution cooperation in the Yangtze River Delta exhibits a typical "multi-center" network structure, with Shanghai-Suzhou, Nanjing, and Hangzhou as the core, forming three city clusters with tighter cooperation. Suzhou, Shanghai, and Jiaxing have the highest degree of centrality, which are 51, 46, and 44, respectively. The analysis of degree centrality reveals that cities with higher levels of economic development or those that serve as provincial capitals often play a leading role in the cooperation network. The study also observes that adjacent cities or local governments closer to the core cities are more likely to establish cooperative relationships; this phenomenon is not limited by provincial administrative boundaries.